Disclosed is a method of fabricating a semiconductor image sensor device. The method includes providing a substrate having a pixel region, a periphery region, and a bonding pad region. The substrate further has a first side and a second side opposite the first side. The pixel region contains radiation-sensing regions. The method further includes forming a bonding pad in the bonding pad region; and forming light-blocking structures over the second side of the substrate, at least in the pixel region, after the bonding pad has been formed.
Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A method comprising: forming pixel regions within a substrate, the substrate having a first side and a second side opposite the first side; forming light-blocking structures over the second side of the substrate, wherein the light-blocking structures define an opening extending through the light-blocking structures, the opening being aligned with one of the pixel regions; forming a passivation layer within the opening; forming a color filter within the opening; forming an interconnect structure over the first side of the substrate; removing a portion of the substrate from the second side to expose a conductive feature associated with the interconnect structure; and forming a bonding pad on the conductive feature.
A method for fabricating a back-side illuminated image sensor. The process involves creating pixel regions in a substrate that has a front and back side. Light-blocking structures are formed on the back side, defining openings aligned with the pixel regions. A passivation layer is then applied within these openings. A color filter is formed within the opening atop the passivation layer. An interconnect structure is created on the front side of the substrate. The substrate is thinned from the back side to expose a conductive feature linked to the front-side interconnects, and a bonding pad is formed on this exposed conductive feature.
2. The method of claim 1 , wherein the forming of the passivation layer within the opening includes forming the passivation layer over a top surface of at least one of the light-blocking structures, the top surface facing away from the substrate.
The method of forming a back-side illuminated image sensor builds upon the previous description by specifying that the passivation layer, when formed within the openings in the light-blocking structures, extends over the top surface of at least one of the light-blocking structures. This top surface is the one facing away from the substrate. Thus, the passivation layer not only lines the opening but also covers part of the light-blocking structure.
3. The method of claim 2 , wherein the top surface of the at least one of the light-blocking structures remain covered by the passivation layer after forming the color filter within the opening.
This method of creating a back-side illuminated image sensor builds on the previous two descriptions. After the passivation layer is formed over the top surface of at least one light-blocking structure (the surface facing away from the substrate), that top surface *remains* covered by the passivation layer even after the color filter is formed within the opening. The color filter does not displace or remove the passivation from the top of the light-blocking structure.
4. The method of claim 1 , wherein the passivation layer defines a recess within the opening, and wherein the forming of the color filter within the opening includes forming the color filter within the recess defined by the passivation layer.
This method of fabricating a back-side illuminated image sensor builds on the first description. Instead of simply lining the opening with passivation, the passivation layer is formed to create a recess within the opening. This means the passivation layer has a specific thickness and shape, such that a cavity or indentation remains within the opening. The color filter is then formed specifically *within* that recess defined by the passivation layer, effectively filling the cavity.
5. The method of claim 1 , further comprising forming an antireflective coating layer over the second side of the substrate prior to forming the light-blocking structures over the second side of the substrate.
Before forming the light-blocking structures on the back side of the substrate, an antireflective coating is first applied to the back side. After forming pixel regions within a substrate that has a front and back side, the anti-reflective coating is applied to the second side before the light-blocking layers are added. This antireflective coating aims to minimize light reflection and improve light transmission into the pixel regions.
6. The method of claim 1 , wherein the forming of the passivation layer within the opening further includes forming the passivation layer directly on the bonding pad.
This method expands upon the previous descriptions related to forming back-side illuminated image sensors. The passivation layer, when formed within the opening in the light-blocking structure, is applied *directly* onto the bonding pad. Thus, the passivation layer makes physical contact with the material of the bonding pad.
7. A method comprising: forming a radiation sensing region in a substrate, the substrate having a first side and a second side opposite the first side; removing a portion of the substrate from the second side to expose a conductive feature; forming a bonding pad on the conductive feature; forming radiation-blocking structures over the second side of the substrate, wherein the radiation-blocking structures define an opening extending through the radiation-blocking structures; forming a passivation layer within the opening, wherein the forming of the passivation layer within the opening includes forming the passivation layer directly on the bonding pad; and forming a color filter within the opening.
A method for fabricating a back-side illuminated image sensor involves forming a radiation-sensing region in a substrate. The substrate has a front and back side. The substrate is thinned from the back to expose a conductive feature, on which a bonding pad is formed. Radiation-blocking structures are built on the back side, creating an opening. A passivation layer is formed in the opening, making direct contact with the bonding pad. Finally, a color filter is placed in the opening.
8. The method of claim 7 , further comprising removing a first portion of the passivation layer to expose a first portion of the bonding pad while a second portion of the passivation layer covers a second portion of the bonding pad.
This method of creating a back-side illuminated image sensor builds upon the previous claim by adding a step: after forming the passivation layer directly on the bonding pad within the opening in the radiation-blocking structures, *part* of the passivation layer is removed. This exposes part of the bonding pad, while another part of the passivation layer *still covers* a different part of the bonding pad.
9. The method of claim 8 , further comprising forming another conductive feature directly on the first portion of the bonding pad while the second portion of the passivation layer covers the second portion of the bonding pad.
Building upon the previous description (creating an image sensor by selectively removing passivation), another conductive feature is formed directly on the now-exposed portion of the bonding pad. This occurs while a different part of the passivation layer still covers another portion of the bonding pad. This implies creating a second conductive layer connecting directly to the bonding pad in a partially passivated area.
10. The method of claim 8 , wherein the forming of the color filter within the opening occurs after removing the first portion of the passivation layer to expose the first portion of the bonding pad while the second portion of the passivation layer covers the second portion of the bonding pad.
The process of fabricating a back-side illuminated image sensor proceeds as previously described (forming radiation-blocking structures, a passivation layer directly on the bonding pad, and selectively removing part of the passivation to expose part of the bonding pad). The formation of the color filter within the opening in the radiation-blocking structures happens *after* the passivation layer has been partially removed to expose part of the bonding pad.
11. The method of claim 7 , further comprising forming a dielectric isolation feature in the substrate, and wherein the removing of the portion of the substrate from the second side to expose the conductive feature includes removing a first portion of the dielectric isolation feature while a second portion of the dielectric isolation feature remains within the substrate.
In this image sensor fabrication method, after a radiation sensing region is created, a dielectric isolation feature is also formed within the substrate. When the substrate is thinned from the back to expose a conductive feature, part of the dielectric isolation feature is also removed, but another part of that dielectric isolation feature *remains* within the substrate.
12. The method of claim 11 , wherein the dielectric isolation feature is a shallow trench isolation structure.
The previously described method for image sensor fabrication that incorporates a dielectric isolation feature specifies that the dielectric isolation feature is a shallow trench isolation (STI) structure. Thus, the dielectric isolation is achieved using a trench filled with a dielectric material.
13. The method of claim 11 , wherein the forming of the passivation layer within the opening includes forming the passivation layer directly on the second portion of the dielectric isolation feature.
Building on previous image sensor process steps, after partially removing a shallow trench isolation structure, forming a passivation layer within the opening created by radiation blocking structures also entails forming that passivation layer *directly* on the portion of the shallow trench isolation structure that remains.
14. The method of claim 7 , wherein at least one of the radiation-blocking structures includes a metal material.
In the described method for making a back-side illuminated image sensor, the radiation-blocking structures (which define an opening), include a metal material in at least one layer.
15. A method comprising: forming a first radiation sensing feature and a second radiation sensing feature in a substrate, the substrate having a first side and a second side opposite the first side and an interconnect structure disposed over the first side; removing a portion of the substrate from the second side to expose a portion of the interconnect structure; forming a conductive feature on the portion of the interconnect structure; forming radiation-blocking structures over the second side of the substrate, wherein the radiation-blocking structures define an opening extending through the radiation-blocking structures; forming a passivation layer within the opening; and forming a color filter within the opening.
The method of creating an image sensor involves forming two radiation sensing features (first and second) in a substrate. The substrate has a front and back side, and an interconnect structure exists on the front side. Part of the substrate is removed from the back to expose part of this interconnect structure. A conductive feature is formed on this exposed part of the interconnect. Radiation-blocking structures are then built on the back, creating an opening. A passivation layer and color filter are then formed within the opening.
16. The method of claim 15 , wherein the forming of the radiation-blocking structures over the second side of the substrate occurs after removing the portion of the substrate from the second side to expose the portion of the interconnect structure.
In this image sensor fabrication process, the step of forming radiation-blocking structures on the back side of the substrate, which define an opening, occurs *after* the substrate has been thinned from the back to expose the portion of the interconnect structure.
17. The method of claim 15 , wherein a portion of the substrate is disposed between an edge of the first radiation sensing feature and the second side of the substrate, wherein the edge of the first radiation sensing feature faces the second side of the substrate.
In the described image sensor fabrication, a portion of the substrate material remains between the edge of the first radiation sensing feature and the back side of the substrate. The "edge" refers to the part of the first radiation sensing feature that is closest to, and faces, the back side of the substrate.
18. The method of claim 15 , wherein the forming of the passivation layer within the opening includes forming the passivation layer directly on the conductive feature.
Building on the previous image sensor fabrication description, when the passivation layer is formed within the opening in the radiation-blocking structures, that passivation layer makes *direct* contact with the conductive feature that was previously formed on the exposed interconnect structure.
19. The method of claim 15 , further comprising forming an antireflective coating layer over the second side of the substrate, and wherein the forming of the passivation layer within the opening includes forming the passivation layer directly on the antireflective coating layer.
This method also forms an antireflective coating layer over the back side of the substrate. Building on the other image sensor fabrication descriptions, when the passivation layer is formed within the opening, the passivation layer makes *direct* contact with this antireflective coating layer.
20. The method of claim 15 , further comprising forming buffer layer over the second side of the substrate, and wherein the forming of the passivation layer within the opening includes forming the passivation layer directly on the buffer layer.
This method also includes forming a buffer layer over the back side of the substrate. Building on the other image sensor fabrication descriptions, when the passivation layer is formed within the opening, the passivation layer makes *direct* contact with this buffer layer.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
October 4, 2016
October 10, 2017
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.